1. Field of the Invention
The present invention relates to high-pressure steam sterilizers for sterilizing clothes or instruments for use in medical purposes.
2. Description of the Related Art
Conventionally, autoclaves are generally used for sterilizing articles such as clothes or instruments for use in medical purposes due to its low cost for introduction and availability of water that is harmless to humans. Autoclaves sterilize medical instruments by a process of steaming under high pressure. Specifically, autoclaves contains in its chamber articles to be sterilized, removing air in the chamber by a vacuum pump, then supplying high-pressure steam, so as to sterilize the articles.
If and when steam permeates poorly (insufficiently) into articles to be sterilized, desired sterilization effect is not achieved. Thus, tests by a process challenge device (PCD) have been conventionally performed, so as to determine whether steam has permeated well or not into articles to be sterilized with monitoring an indicator.
A test by the PCD is carried out by providing an indicator for showing some reaction on exposure to steam and a steam permeable body for giving a predetermined resistance to steam flowing therethrough, then passing steam through the steam permeable body to the indicator, and determining an amount of steam that has reached the indicator based on reaction degree of the indicator so as to measure an sterilization effect. The test is carried out in daily sterilization. The steam permeable body to be used generally meets the AAMI (Association for Advancement of Medical Instrumentation) standard in the United States and is made in the following way. Surgical towels are cut into predetermined dimensions, further folded in a predetermined way, and used with stacked in 16 pieces. An indicator is interposed between the seventh and eighth pieces. The entire 16 pieces of towels including therein the indictor are secured with tape, forming steam permeation resistance (steam permeable body) to the indicator. The towels having been used are washed, dried, and then reused.
The test performed by the AAMI standard requires such complicated preparations as described above, and further requires the need and time to wash and dry the towels for reuse thereof. There is another test called the Bowie & Dick test different from the test performed by the AAMI standard in sterilization. The Bowie & Dick test is different from the test performed by the AAMI standard in its specification, but the purpose of determination of a sterile condition is common to the both. An indicator for simplifying a test equivalent to the Bowie & Dick test is disclosed, for example, in the patent document 1.
Patent Document 1: Japanese Patent No. 3130557